{"doi":"10.1002/mrm.30368","title":"Proton‐free induction decay <scp>MRSI</scp> at <scp>7 T</scp> in the human brain using an egg‐shaped modified rosette K‐space trajectory","abstract":"PURPOSE: H)-MRSI via spatial-spectral encoding poses high demands on gradient hardware at ultra-high fields and high-resolutions. Rosette trajectories help alleviate these problems, but at reduced SNR-efficiency because of their k-space densities not matching any desired k-space filter. We propose modified rosette trajectories, which more closely match a Hamming filter, and thereby improve SNR performance while still staying within gradient hardware limitations and without prolonging scan time. METHODS: Analytical and synthetic simulations were validated with phantom and in vivo measurements at 7 T. The rosette and modified rosette trajectories were measured in five healthy volunteers in 6 min in a 2D slice in the brain. An elliptical phase-encoding sequence was measured in one volunteer in 22 min, and a 3D sequence was measured in one volunteer within 19 min. The SNR per-unit-time, linewidth, Cramer-Rao lower bounds (CRLBs), lipid contamination, and data quality of the proposed modified rosette trajectory were compared to the rosette trajectory. RESULTS: Using the modified rosette trajectories, an improved k-space weighting function was achieved resulting in an SNR per-unit-time increase of up to 12% compared to rosette's and 23% compared to elliptical phase-encoding, dependent on the two additional trajectory parameters. Similar results were achieved for the theoretical SNR calculation based on k-space densities, as well as when using the pseudo-replica method for simulated, in vivo, and phantom data. The CRLBs of γ-aminobutyric acid and N-acetylaspartylglutamate improved non-significantly for the modified rosette trajectory, whereas the linewidths and lipid contamination remained similar. CONCLUSION: By optimizing the shape of the rosette trajectory, the modified rosette trajectories achieved higher SNR per-unit-time and enhanced data quality at the same scan time.","journal":"Magnetic Resonance in Medicine","year":2024,"id":476135,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":3,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.956,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1009979,"name":"Lukas Hingerl","orcid":"0000-0003-1808-8349","position":1,"is_corresponding":false},{"id":489090,"name":"Małgorzata Marjańska","orcid":"0000-0002-4727-2447","position":2,"is_corresponding":false},{"id":256334,"name":"Wolfgang Bogner","orcid":"0000-0002-0130-3463","position":3,"is_corresponding":false},{"id":1047434,"name":"Stanislav Motyka","orcid":"0000-0002-6314-316X","position":4,"is_corresponding":false},{"id":856611,"name":"Gilbert Hangel","orcid":"0000-0002-3986-3159","position":5,"is_corresponding":false},{"id":581259,"name":"Antoine Klauser","orcid":"0000-0003-3019-9914","position":6,"is_corresponding":false},{"id":256331,"name":"Ovidiu C. Andronesi","orcid":"0000-0002-7412-0641","position":7,"is_corresponding":false},{"id":410063,"name":"Bernhard Strasser","orcid":"0000-0001-9542-3855","position":8,"is_corresponding":false},{"id":1313390,"name":"Simon Blömer","orcid":"0009-0005-3924-0575","position":0,"is_corresponding":true}],"reference_count":49,"raw_metadata":null,"created_at":"2026-07-19T02:06:25.428435Z","pmid":"39568225","pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}